1. Field of the Invention
The present invention relates generally to electric power supplies, and more specifically to redundant, automatic switching power supplies. Even more specifically, the present invention relates to inputs to redundant power supplies.
2. Discussion of the Related Art
For many critical or important electrical and/or electronic equipment or systems, it is desirable to have an alternate, or xe2x80x9cstandby,xe2x80x9d power source if a primary power source is lost or becomes unreliable.
A few examples of such equipment or systems are computer systems for hospital operating rooms and critical care equipment, air traffic control systems, police and fire emergency equipment, telecommunications systems, and national security systems. As may be imagined, the failure of a power supply to deliver a predictable power can have serious and potentially dangerous consequences.
It is, therefore, common to provide standby electrical power supplies to provide redundant power to a primary power supply. Commonly, the primary power is supplied by a local utility company at, e.g., 240 volts AC or 120 volts AC at 60 Hertz.
Many types of standby power sources are available, including turbines, micro-turbines, battery powered inverters, rotary engines, internal combustion engines, and more recently, high-speed electrical generators and flywheels have been developed. These standby power sources may vary from the primary power in terms of voltage, phase and frequency. Thus, the primary and standby power supplies may be unsynchronized, and if the primary and secondary supplies are applied to a load simultaneously, potentially harmful voltage spikes and current surges may occur.
To prevent interaction between primary and standby alternating current power sources some redundant power supplies have elaborate break-before-make switching to assure that sources of different voltages, phase and frequency do not get connected together.
In other applications, for example where a load operates from redundant direct current, some redundant power supplies connect the primary and standby supply inputs with diodes after each input has been full wave rectified. This type of configuration, however, does not eliminate the possibility of voltage multiplication if, for example, primary and standby sources are operating from different grounds.
The present invention advantageously addresses the needs above as well as other needs by providing a power input architecture for use with redundant power supplies.
In one embodiment, the invention can be characterized as a power input architecture for a computing system including a first input module comprising a second input module inhibitor and a first input module switch wherein the first input module is configured to receive power from a first power source wherein the first input module switch detachably couples the first input module to a power supply system for the computing system. The power input architecture also includes a second input module comprising a first input module inhibitor and a second input module switch wherein the second input module is configured to receive power from a second power source wherein the second input module switch detachably couples the second input module to the power supply system for the computing system. The first and second power input modules and the power supply system for the computing system are configured to be housed in a chassis of the computing system, and the second input module inhibitor is coupled to the second input module switch and is configured to provide a second input module inhibit signal wherein the second input module switch is configured to open in response to the second input module inhibit signal.
In another embodiment, the invention can be characterized as a method, and means for accomplishing the method, of providing input power to a computing system, the method including the steps of: receiving a first voltage from a first power source at a first input module wherein the first input module is detachably coupled to the computing system; communicating an inhibit signal from the first input module to a second input module in response to the first voltage from the first power source being at least a first predetermined voltage level; receiving a second voltage from a second power source at the second input module wherein the second input module is detachably coupled to the computing system; isolating the second voltage received at the second input module from the power supply system in response to the inhibit signal from the first input module being received at the second input module; providing power from the first power source to a power supply system for the computing system through the first input module in response to the first voltage from the first power source being at least the first predetermined voltage level; and providing power from the second power source to the power supply system for the computing system through the second input module in response to both the inhibit signal from the first input module not being received at the second input module and the second voltage being at least a second predetermined voltage level.